New Functionality in Version 4.2

A Lumped Port boundary feature is now available in the
Magnetic Fields interface and in the Magnetic and Electric Fields
interface. This feature is used for easier excitation of coils and
other conducting structures. It also gives access to S-parameters.

Reduced Potential formulations of the Magnetic Fields and
Magnetic Fields, no currents interfaces as previously available in
version 3.5a are now supported.

Small signal analysis is now available. The implementation
is different and more general than in version 3.5a; a tutorial example
model, Small Signal Analysis of Inductor, is provided.

In the Electric Currents interface capacitive terms has been
added to the Distributed Resistance feature and the name has
changed to Distributed Impedance. Similarly, the Contact
Resistance feature has changed and is now called Contact
Impedance. There is also a Pair Contact Impedance available
on assembly pairs. All of these features allow for setting dielectric
properties for capacitive coupling across the layer in addition to
electrical conductivity for resistive coupling. In the stationary
study, the dielectric properties are not used.

The following addition to the new functionality in COMSOL
Multiphysics is of special interest for users of the AC/DC Module:

Nyquist Plots are available in 1D Plot Groups.

Logarithmic arrow length scaling is now provided for Arrow
plots.

Backward Compatibility vs. Version 3.5a

Change in Dependent Variables

Version 4 has a comprehensive set of inductive formulations based on
the magnetic vector potential. These cover all modeling situations
except for situations with strongly nonlinear conductivity
(superconductors) for which magnetic field H-based formulations are more
suitable.

The 2D formulations based on the magnetic field H as dependent variable in version
3.5a are not yet included in version 4.1. A full set (3D, 2D and 2D
axisymmetry) of H based
formulations is planned for a future release.

Models created in version 3.5a that are built using an H based formulation will not include
any physics interface settings when opened in version 4.1. Geometrical
data and definitions (constants and expressions) will be imported and
the physics can manually be added using the (vector potential based)
Magnetic Fields physics interface.

Pair Boundary Conditions

The Contact Resistance, Transition, and Perfect Magnetic Conductor
boundary conditions are not yet available as assembly Pair boundary
conditions.

A new set of slit-based, discontinuous boundary conditions, which
does not require assemblies is introduced in version 4. In most models,
this can replace the assembly pair boundary condition.